Quantum key distribution is regularly touted as the encryption of the future. While the keys are exchanged on an insecure channel, the laws of physics provide a guarantee that two parties can exchange a secret key without knowing whether they're being overheard. This unencrypted-but-secure form of key exchange circumvents one of the potential shortcomings of some forms of public key systems.
However, quantum key distribution (QKD) has one big downside: the two parties need to have a direct link to each other. So, for instance, banks in and around Geneva use dedicated fiber links to perform QKD, but they can only do this because the link distance is less than 100km. These fixed and short links are an expensive solution. A more flexible solution is required if QKD is going to be used for more general encryption purposes.
A group of Italian researchers have demonstrated the possibility of QKD via a satellite, which in principle (but not in practice) means that any two parties with a view of a satellite can exchange keys.
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